Motorola Axiom CMD11E1 Guía de usuario descargar pdf (Pagina 61)

5.5. WORKING WITH TABLES 61

a Yes/No value. A convenient way to return a Yes/No value is to use a hardware

ﬂag. Let us use the Carry ﬂag. The function will set the ﬂag if the answer is yes;

or else it will clear the carry.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; lookup: Function to lookup a value in a table

; Checks if the value in A register is in the table

;

; Entry: Starting address in X, size in B, value in A

; Exit: Carry set if the value in A is in the table;

; cleared if not in the table

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

lookup

lkploop

tstb

beq notthere *this is the basic counting loop

cmpa 0,x

beq foundit

inx

decb

bra lkploop

notthere

clc

rts

foundit

sec

rts

Here is a program that uses the function:

;Name:

;email:

;date:

;

; Standard buffalo equates

; Make sure you have ALL the equates in the file.

;

ucase equ $ffa0

wchek equ $ffa3

dchek equ $ffa6

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Motorola Axiom CMD11E1 Guía de usuario Pagina 61